Physical inactivity is a major risk factor for cardiovascular disease. Less than half of American adults meet current physical activity (PA) guidelines for 150 minutes of moderate or 75 minutes of vigorous aerobic activity each week. Women, especially working women, are less likely than men to meet PA guidelines known to prevent disease and promote health. The purpose of this preliminary study is to deliver a 12-week, workplace intervention to increase PA among working women. Using an experimental study design, physically inactive women working in a large Midwestern health system (n = 60) will be randomized to either the intervention group (n = 30) or the attention control group (n = 30). All participants will receive an exercise prescription based on fitness testing. The intervention group will: 1) be encouraged to increase physical activity behavior to meet current guidelines for 150 minutes of moderate intensity aerobic PA per week and 2) participate in six semi-structured peer group meetings with six different successful peer models. The pre-selected peer models are fellow employees who meet current PA guidelines (at least the past 6 months) and will be trained to share the practical aspects of their success to being physically active. Topics to be presented to the intervention group include: motivation for PA, barriers and facilitators of PA, self-monitoring behavior, goal setting, and technology used to facilitate PA. The attention control group will participate in six informational sessions on cancer prevention and detection in women. The specific study aims are to: 1) assess the feasibility of implementing the INSPIRATION Intervention for the first time by evaluating the number of contacted/recruited participants, number of drop-outs, time for intervention delivery, amount of missing data and adherence to the intervention; 2) determine the effect of a peer-modeling workplace intervention on the primary outcome of cardiorespiratory fitness (CRF), and secondary outcomes of physical activity behavior, lifetime cardiovascular risk, PA self-efficacy, and social comparison; and 3) describe intervention participants' perceptions of a PA peer-modeling workplace intervention using qualitative data. The qualitative data will include: a) a one-time, focus group sub-sample of 10 intervention participants varied by age, ethnicity and occupation, b) investigator field notes from peer meetings, and c) participant intervention evaluation survey. Outcomes to be measured at both time points (baseline and 12 weeks) in both groups include: cardiorespiratory fitness (cycle ergometer), PA (measured by ActiGraph GT3X), cardiovascular risk, self-efficacy for PA, and social comparison behavior. To understand the participant perspective of the intervention, qualitative inquiry using focus-group methods will be used in a sub-sample of the intervention group. This workplace peer-modeling intervention to increase PA in working women is an innovative intervention strategy that has the potential to be implemented in other settings and with other populations.